1. Field of the Invention
The invention concerns an oval package, especially for cosmetic sticks, with an improved mechanism for retaining a cap onto a container body of the package.
2. The Related Art
Current packages for cosmetic sticks and the like normally utilize friction or screw threads to affix a cap to a container body. Unfortunately, friction does not hold well. A screw thread is more secure but requires more effort to detach the cap. Accordingly, there is much interest in developing a cap retention mechanism which enjoys the ease of removal characteristic of friction, yet maintains a reasonable retention security characteristic of screw threads.
The art has described a number of improvements in this area. For instance, U.S. Pat. No. 2,718,980 (Strom) discloses a capsule-shaped container having a cover and a body portion. The cover portion is provided with a bead and a groove which engage corresponding groove and bead structures on the body portion.
U.S. Pat. No. 3,244,272 (Beaman et al.) reports a coin tube having a cap and a body portion wherein four lugs on the cap snap fit into four grooves of the body of the coin tube.
U.S. Pat. No. 4,098,421 (Forster) describes a closure for a container having a cover and a body portion which snap together resiliently to close the container. Ribs formed on the body project outwardly while ribs formed on the cap project inwardly. These ribs resiliently snap past one another and then engage on an underside with a detent action to hold the cover onto the body.
None of the aforementioned mechanisms have found particular use with oval-shaped packages. These oval packages present a special difficulty in providing a proper snap-fit.
A problem especially associated with cosmetic sticks of the antiperspirant and deodorant variety is that of crystallization induced by pressure from the package. Cosmetic stick compositions such as deodorants and antiperspirant are often poured hot into the container which is then capped. Upon cooling the container shrinks along with the product. Pressure from the cap retention structures then provide points of crystallization for the cooling stick. Crystallization is quite undesirable. Thus, it is important to avoid retention structures which apply pressure against the container body which may be transmitted to the stick composition.
Accordingly, it is an object of the present invention to provide an oval package with an improved retention mechanism between cap and body.
Another object of the present invention is to provide an oval package with a retention mechanism that achieves a positive hold between cap and container but nevertheless, is easily separable through a snap action.
A still further object of the present invention is to provide an oval package for a cosmetic stick which overcomes the problems of stick crystallization caused by cap stress on the package.
These and other objects of the present invention will become more evident through the following summary, examples and detailed description.